Need some advice on turbo compressor wheel sizing.... - Honda Prelude Forum

Spocko · 11-13-2001, 08:53 PM

I am upgrading my current compressor wheel to a TO4 super E(I currently have a TO4E .50) but am unsure which wheel trim would be the best choice for me. Some at turbonetics have suggested that the .50 trim is too undersized for the H22a and have suggested a 57 or 60. I need some feedback as how to determine how the trim will affect my performance. Also is there any benefit to upgrade the turbine wheel as well. Not even sure what the hell T3 wheel is in there, but what is a good one to get.

I also am toying with the notion of upgrading to ceramic BB as well to combat lag, which also makes the notion of getting a larger trim wheel ok since I will be countering the increased lag with the BB(and the "super" type wheel.

Basically I am looking for a kit that delivers STRONG power in mid range and keeps pulling harder and harder as the rpms climb. It doesn't have to spool up to full potential very low in the rpms, as I will be running 15-18 psi with it and could use a little spool up time to get the tires hooked up(street racing and daily driving are what I use my lude for for 95% of the time). Any tips, guidelines, comparos, differences, calculations, formulas, etc are greatly appreciated here.

BlueShadow · 11-16-2001, 07:59 PM

Wassup Spocko,

Although I'm not a turbo expert (yet) I've been going over some calculations to figure out the right Compressor size. As far as I know you have to calculate the airflow under boost at 2 RPM points then you take the CFM under boost (CFM/B)and the pressure ratio and reference those onto the compressor maps that turbonetics has available (you want the pressure ratio and the CFM/B to intersect on the area of the chart where there is the greatest efficiency percentage)

confused yet? If I'm wrong though I won't mind anyone correcting me. let me show you the calculations for figuring out the above.

AIRFLOW W/NO BOOST
(CID x RPM x 0.5 x VE) / 1728
CID = Cubic inch displacement (61 x # of Liters = CID)
RPM = revolutions per minute
0.5 = 4-stroke engine fills cylinder only on one-half the revolutions number is a given
VE = Volumetric Efficiency (don't know what it is for an H22 so I use 85%)
1728 converts cubic inches to cubic feet

so for example the CFM for a 2.2L Lude @7200 RPM =
(134.2 x 7200 x 0.5 x 0.85) / 1728 = 237.65 CFM (no boost, atmospheric)

CALCULATING PRESSURE RATIO
pressure ratio = (14.7 + boost in PSI) / 14.7
so for example the pressure ratio for a car with 15 PSI of boost =
(14.7 + 15) / 14.7 = 2.02 (pressure ratio)

CFM WITH BOOST
CFM w/boost = CFM @ atmo x your pressure ratio
now using the above two examples of
--CFM of a 2.2L (134.2 cid) @7200rpm at atmosphere (14.7 PSI)
--your pressure ratio (2.02)

CFM x pressure ratio = CFM under boost
237.65 x 2.02 = 480.05 CFM

So unless I messed up somewhere:
a 2.2L @7200 RPM WITH 15 PSI of boost has a CFM of 480.05 and a pressure ratio of 2.02

You still have to calculate the air density ratio, the intercooler PSI loss and the Air filter loss (if you have one) because each one of those raises the temperature of the air charge and thats bad especially if you are unaware or do not take them into account.

Then you have to get the properly sized Turbine with the correct A/R ratio. I don't know how to get the right size but from what I've read its a process of guess-timation and trial and error. Three things I do know though
#1 the Exducer bore size is and good way to tell what the CFM intake rate is

#2 if the A/R is to BIG, boost rise is sluggish, if it's too big it might keep the turbo from turning fast enough to produce the desired boost

#3 if the A/R is to SMALL, the turbo response will be quick and will feel jumpy. It will also start to lose power towards the upper thirdof the engine's rev range.

(courtesy of the book MAXIMUM BOOST by Corky Bell)

BlueShadow · 11-16-2001, 08:15 PM

THIS MAP WAS WRONG SO I DELETED IT THERE'S A NEW ONE I MADE JUST SCROLL DOWN.

BlueShadow · 11-16-2001, 08:43 PM

I was trying to draw a Compressor map above but heres a pic of one. I got it from www.turbocharged.com the only problem is the bottom of the map is in lbs/min and I did the CFM.

So does anyone know how to convert cubic inches to pounds per minute? or cubic feet to pounds per minute?

But anyways I think you're supposed to see where your pressure ratio (right side) and your CFM or lbs/min (bottom side) intersect. ideally you want it to be in the highest compressor efficiency % (76%, 73% 70% on the map)

The numbers on the right 69800, 84000, 98300 etc is the RPM of the compressor. You can also see the line that extends from each of those numbers into the map.

And this is just a theory of mine but I think the RPM of the compressor should be kept as low as your pressure ratio and CFM or lbs/min should allow.

This chart is for the T04E 40"

Spocko · 11-17-2001, 11:33 AM

Hey man thanks a lot! They should flag this in the FAQ section. I have decided to go with a stage 2 T3 turbine wheel and a TO4 Super E .50 trim wheel along with a ceramic ball bearing upgrade(basically ordered a new turbo). This should be the most efficient turbo for my needs.

00G · 11-17-2001, 11:51 AM

You may want to check this page out:

http://www.turbofast.com.au/turbomap.html

DirtyLude posted the bore/stroke of a stock h22a
I believe it is 3.48"bore and 3.62"stroke. The rest of the info is on the page....

After you input all the info, you can compare between different maps by hitting next/previous map.....

BlueShadow · 11-17-2001, 09:04 PM

Quote:

Originally posted by Spocko
Hey man thanks a lot! They should flag this in the FAQ section. I have decided to go with a stage 2 T3 turbine wheel and a TO4 Super E .50 trim wheel along with a ceramic ball bearing upgrade(basically ordered a new turbo). This should be the most efficient turbo for my needs.

No problem

ONE IMPORTANT THING THOUGH that I should mention is calculating the surge limit of you pressure ratio and CFM @ boost.

If you look at the airflow rate above you'll see it's in CFM, Billy (71DSP) was kind enough to tell me how to convert CFM to lb/min. Most compressor maps I've seen measure airflow rate in lb/min.

TO CONVERT CFM TO LB/MIN
CFM x .078125 = LB/MIN
-- 0.078125 lbs is the weight of 1 cubic foot of air at 48* F @ sea level
-- 0.0625 lbs is the weight of 1 cubic foot of air at 175* F @ sea level

anyways for the other half of selecting your compressor, you can approximate this like so. assume that the the desired pressure ratio is reached at 50% of the redline RPM, 15 PSI (full boost @ 3600 RPM for our example.

We now need to find our CFM UNDER BOOST @ 3600 RPM, you should know how to do this by now.
CFM UNDER BOOST @ 3600 RPM
-(134.2 x 3600 x .5 x .85) / 1728 = 118.82 CFM @ atmo
-118.82 x 2.02 = 240 CFM @ 15 PSI
-240 CFM --> 18.75 LB/MIN

So assuming our 2.2L reaches full boost (15 PSI) at 3600 RPM, the airflow rate 3600 RPM will be 240 CFM or 18.75 LB/MIN

THIS IS THE SECOND POINT I WAS TALKING ABOUT IN MY FIRST POST

now you know
-the airflow rate @ 7200 RPM = 37.5 LB/MIN @ 2.02
-the airflow rate @ 3600 RPM = 18.75 LB/MIN @ 2.02

now when you are looking at acompressor map, mark of these two RPM points and draw a line from one too the other.
this line represents your you airflow rate once you hit full boost (3600 RPM) and the line going to 7200 RPM (redline) is your RPM range.
this line will be a straight horizontal line. you can also see what compressor effiency a particular RPM will be on the compressor map at any time.

-If a boost spike was to occur you can visualize it on this chart as an upwards spike in the RPM range (line).
-If a boost leak/loss was to occur you will see it as a downward slope/spike in the RPM range (line)

still with me? now for the last part of finding the surge limit.....

CALCULATING SURGE LIMIT
-Find the point at which the engine starts to make full boost (3600 RPM in our case)
-Draw a line from this point to a point at PR = 1 and CFM = 20% of MAXIMUM, or 96 CFM in this example. It is imperative that this line lie completely to the right of the surge line on the compressor map.

BlueShadow · 11-17-2001, 09:44 PM

On my above post this is assuming that the engine reaches full boost at 3600 RPM, it might actually reach full boost at 5000 RPM. I just used 3600 as an example.

Heres what the line should look like on the compressor map just picture the compressor map in the background. The numbers along the left side are the pressure ratios and the number along the bottom is the airflow rate (LB/MIN)

3.2 .................................................. ....
3.0 .................................................. ....
2.8 .................................................. ....
2.6 .................3600 RPM.......................
2.4 ....................|................................
2.2 ....................V................................
2.0 ....................O---------------O <-- 7200 RPM
1.8 ................./....................................
1.6 .............../......................................
1.4 ............/.........................................
1.2 ........../...........................................
1.0 ......../.............................................
__0__5__10__15__20__25__30__40__50 <LB/MIN

BlueShadow · 11-17-2001, 10:15 PM

Spocko, I was wondering If I can use you as an example.

I want to use your numbers and do all these calculations and plot the numbers on the T04E .50" compressor map, just for practice.

let me see If I have this right

you have a 2000 prelude 2.2L
-18 PSI is your goal
-7400 RPM redline
-did turbonetics tell you at what RPM it will reach full boost at?
-do you plan on running an air filter? (need to calculate air filter PSI loss)
-what intercooler do you have? so you know what the effeciency is?(need to calculate intercooler PSI loss)

I'm not trying to grill you, I just wanted to put my math to good use instead of doing theoretical situations.

Spocko · 11-18-2001, 09:44 PM

Okay- NFC on what size my intercooler is- it is an apex one that fits basically the entire area of the front grill from foglight to foglight. Also, my desired boost is 20 psi(maybe 25 if I can push it that high, but for now work with 10-20 psi, as 10 will be my new minumum WG spring, and with that I can go to at least 20 psi. Yes I am using a K&N air filter(conical shape ones like on the AEM CAI's). BTW, I am using a TO4 SUPER E .50, not a standard TO4e .50 wheel. Hope this helps, and BTW I am amazed at the info you provided- unfortunately I can't make heads or tails or it. Too tired right now to try either.

Spocko · 11-18-2001, 09:45 PM

Forgot, full boost should be about 3700.

BlueShadow · 11-18-2001, 11:21 PM

WOW! 25 PSI? thats pushing 550 HP. all the stuff I just went over is easy just a lot of adding, subtracting, multiplying and dividing. I just tried figuring out air velocity through a throttle body and that ish is frickin confusing!

oh and FYI: power gain = (PSI / 14.7)x original HP + original HP

so for 20 PSI, (20 / 14.7) x 200 + 200 = 472 HP
and for 18 PSI (18 / 14.7) x 200 + 200 = 445 HP

EDIT I don't know how reliable this is just something I read.

what size injectors you planning on running? you're probably gonna have to run 800+ injectors. Didn't you say you were gonna run a HONDATA?

here's some more FYI's:
size of injectors in lb/min= (expected HP x 0.55) / number of injectors

cc = lb/min x 10.5

injector size = (550 HP x 0.55) / 4 = 75.625 lb/min

75.625 lb/min x 10.5 = 794.06 cc required

bgod · 11-26-2001, 09:31 AM

spocko, you may want to go with a larger trim if you plan to boost close to 20psi.

i used to run a 57 trim, stage 3, .63a/r. what a/r is your tubine.

Spocko · 11-26-2001, 10:12 PM

I am currently running RC Saturated 440 cc injectors right now. I wasn't planning on upgrading them, as if I did they would have to be converted to peak and hold, plus I'd have to get a resistor pack and probably a new distributor(OBD-1) as well. Besides, can I run 800cc injectors daily, and what the hell kinda fuel pressures would I be running at idle?

BlueShadow · 11-27-2001, 02:08 AM

Quote:

Originally posted by Spocko
I am currently running RC Saturated 440 cc injectors right now. I wasn't planning on upgrading them, as if I did they would have to be converted to peak and hold, plus I'd have to get a resistor pack and probably a new distributor(OBD-1) as well.

So you plan on running a Hondata eh? I can't really comment on Hondata cause I dont know much about its tuning options. But I know this what Hondata lacks in tuneability it makes up for with knowledge and specialization, Standalones are the opposite, altough they have a WIDE range of tuneability, they lack support for us Honda folks. I think I read that DirtyLudes website.

Quote:

Originally posted by Spocko
Besides, can I run 800cc injectors daily, and what the hell kinda fuel pressures would I be running at idle?

I just threw that number out as an example, you can probably get away with running smaller injectors, BUT, you just increase the duty cycle or up the fuel pressure to make up for fuel. But I'm not a fuel system expert so you might wanna get with someone else to double check.

I'm sure Hondata has a feature that allows you to adjust fuel at Idle/off-boost conditions.

Smilez · 11-27-2001, 09:09 AM

You would need to use an FPR to increase fuel pressure, then input that new pressure rating into hondata. Personally I don't like the idea of extremly high fuel pressure, that is part of the reason I wanted to go to hondata and 550cc injectors. There are people that have tuned 720cc injectors running hondata and they say their idle is fine. I haven't done the math, but I think 440s would be too small even with high psi for 20lbs.

If you are running hondata, and got something like 720s, then your fuel pressure would remain stock. You don't need to get a new distributor. I am curious why larger injectors would require that?

Spocko · 12-02-2001, 12:32 PM

Yeah, I am thinking about getting 800 cc injectors now(Saturated- which will work fine with my Hondata) in order to keep the duty cycle from maxing out. I also am planning on keeping boost max at 20 psi, but most likely will not run more than 18 max on the street- my Tial 35 mm WG will only allow up to 20 psi safely due to limitations in the internal valve. At 18-20 psi, I still expect to make 400 whp(that is with fully balanced and blueprinted bottom end after JE 9:1's and Eagle rods, along with a port and polish, tuning my Skunk2 cam gears, and after installing my 3" DP with open WG dump and full 3" cat and 3" custom cat-back).

400 whp is a pretty reasonable expectation for these mods, especially after the new turbonetics turbo I'm getting(well actually I am keeping my current Housings, mainly because they are already HPC extreme heat coated- but a whole new internal cartrige is going in, including upgrades to a stage 2 T3 turbine wheel, upgraded TO4 Super E .50 trim, ceramic BB upgrade, all balanced).

I am also upgrading the clutch to a RPS stage 3 turbo clutch with 6-puck carbon claw. From what I hear from knowledgeable turbo luders, this is the best street driven clutch you can get for our cars, as they are good up to about 700 fly hp, and are pretty easy to engage after 1K breal-in period.

So if anyone is looking to do a turbo project correctly, email me as I now have some great parts for sale, including...

94 GSR OBD1 (P72) ECU- $300
RC 440 cc injectors(saturated- 2 months old)- $275- no clips(I need the old ones for my new RC injectors, but you can get a new set from them for $40)
Spoon racing thermostat- used 1 month- $70

All prices include shipping to 48 states